Active Record Ruby

Account.find :all, :conditions => { :first_name =>  @first_name,
                                    :last_name => @last_name,
                                    :favorite_band_id => nil }
which would result in the following SQL query:
SELECT *
  FROM accounts
  WHERE
    first_name = 'John'
    AND last_name = 'Doe'
    AND favorite_band_id IS NULL